Such vehicle body rear part structures, designed with consideration given to rear-side collisions, are known in the art, e.g., as disclosed in Japanese Patent Application Laid-Open Publication No. 2006-96185 (JP-A 2006-096185) and Japanese Patent Application Laid-Open Publication No. 2008-56189 (JP-A 2008-056189).
FIG. 11 hereof shows the rear part of a vehicle body disclosed in JP-A 2006-096185.
The rear half of the vehicle body 100 shown in FIG. 11 comprises a front floor panel 101, left and right floor frames 102, a rear floor panel 103, left and right rear side frames 104, and a cross member 105. The left and right floor frames 102 extend in a longitudinal direction of the vehicle body underneath the front floor panel 101. The left and right rear side frames 104 extend in the longitudinal direction of the vehicle body underneath the rear floor panel 103. The cross member 105 extends between the left and right rear side frames 104. A fuel tank 106 is disposed underneath the rear floor panel 103 and in front of the cross member 105.
The bottom surface of the fuel tank 106 is held on the vehicle body 100 by left and right holding bands 107. The left and right holding bands 107 span between the left and right floor frames 102 and the cross member 105. These left and right holding bands 107 are thin plate-shaped members for holding the fuel tank 106, and the bands do not apply a large amount of resistance (opposing force against a collision load) against a collision load when a rear-side collision occurs.
FIG. 12 hereof shows the rear part of the vehicle body disclosed in JP-A 2008-056189.
The rear part of the vehicle body 110 comprises left and right side sills 111, 111, a front cross member 112, left and right rear side frames 113, 113, a rear cross member 114, and left and right stays 116, 116, as shown in FIG. 12. The front cross member 112 spans between the rear ends of the left and right side sills 111, 111. The left and right rear side frames 113, 113 extend rearward from the rear ends of the left and right side sills 111, 111. The rear cross member 114 spans between the left and right rear side frames 113, 113, and rear suspensions are mounted thereon. The left and right stays (tank frames) 116, 116 extend at an incline from the vehicle-widthwise center of the rear cross member 114 to the rear ends of the side sills 111, 111. A fuel tank 117 is positioned in the space enclosed by the front cross member 112, the left and right rear side frames 113, 113, and the rear cross member 114.
The left and right stays 116, 116 pass underneath the fuel tank 117, and the stays have the function of transmitting loads from the vehicle-widthwise center of the rear cross member 114 to the left and right side sills 111, 111. The left and right stays 116, 116 constitute effective means for dealing with rear-side collisions, but since a pair of left and right stays are needed, a large number of components are involved, leading to a proportionate increase in the vehicle body weight.